Collapsible core



ug. -22, 1939. w, H, COBI 2,170,188

' coLLAPsIBLE CORE Filed pct. 50., 1957 INVENTO Patenied Aug. 22, v1939 f l .l f .UNITED STATES. PA'lfEN-Il l'OFFICE l CoLLAPsmLE CORE Walter II. Cobi, ew vYork, N. Y. Application octoberlso, 193i, semi No. `171,83*:

' zo Claims. (ci. 25-128) Thisl invention relates to collapsible and expansible cores, especially those adapted for use in molds for cementitious materials, and has for p its object tojprovide a simple and inexpensive device of this class which is easy to insert and remove from the cast material after it has at least partially set.

-Another object is to provide such a core which is adapted to. be vself collapsing when the expanding stress has-been removed.

. A further object is to provide means .for limit- 'ing both the vamount of expansibility and the extent to .which the core'may,be collapsible.

Still another object is to provide a exible,

water impervious envelope around said core which is adapted to keep water from flowing into the core.

Referring 'to the drawing- Fig. 1 is a -longitudinal view 'mostly' in section through one embodiment of this invention.

Fig.2 is a section on the line 2--2 of Fig. l

'showing the core in expanded position.

Fig. 3 is a view corresponding to Fig. 2 but with the core 'in `collapsed position. b1

'Fig 4 shows another embodiment of this invention. f

Side members Ill, Il, I2 and I3 may be of any size or shape desired in order to give the`de'sire'd configuration to the core. Ply wood, press wood or aluminum has been found a desirable material for use in constructing 4these side members or blocks. When the core is polygonal in cross section there may be as many side `members as desired, that is, three-or more. YArranged within these side members I0 to I3 is a means I4 for expanding the side members, which in the embodiment illustrated includes a rubber cylinder I4 adapted to be expansible and compressible. A heavy gum rubber has been found-suitable for this purpose.

Surrounding the cylinder I4 is a-means I5 for .A

limiting expansibility of the cylinder I4 and comprising a tube of thin spring brass or its equiva Between the" metal cylinder I5 and the side blocks I0 to I3 are arranged spacing blocks I6, I1, I8 and; I9 which contact with the expansive means for. pressing the side members outwardly.

Surrounding the core is a flexible water'im pervious envelope 20 which is adapted to prevent water from flowing into .the core from the wet cementitious material. This envelope comprises a canvas covering 2| preferably of sail cloth whichis rugged yet adapted to be stretched and the ends oi' the canvas may be turned in adja- Surrounding the canvas 2|- is a waterproof paper 23 which may be loose and just have its ends overlapped without being adhesively secured.4

The canvas 'may if desired be waterproofed and the paper eliminated. The paper may also have its lapped edges held together by a water-f 'proof4 adhesive to form an envelope of the right size. manently secured to the side members.

l Within the core are arranged at spaced intervals a number of very strong rubber bands 2l or other springy material capable of being stressed sutlciently to automatically collapse the core when desired. These'rubberbands 24 are about 3A of an' inch wide by about 1A of an inch thick and-are longitudinally spaced apart about 5 inches. Each of these bands 24 is held in place by the heads on the inne'r ends of pins 25,26, 21and 28, the outer ends of these pins being perforated to receive the supporting pins.

or beams 29, 30, 3land 32. The rubber is substantially stressed in tension at all times so that the pins 25 tov 23 inclusive are likewise intension. The supporting pins 23 to I32 inclusive are each arranged in recesses -33 in the side blocks and the rubber bands 24 are .arranged between longitudinal portions o'f the blocks- I6 to I9 inclusive.

End plugs 34 and 35 of rubber or other appropriate material are vulcanized to the end portions of the rubber cylinder 24 and in addition the ends of the rubber cylinder may be bound around these plugs by stressed-hooks or wrapped wire. Passing axiallythrough the cylinder Il is a tension rod 36, the ends of which are secured to the'plugs and'this rod 38 prevents the cylinder Il from elongating longitudinally an objection- Neither thepaper nor the canvas is per- ,31 for attachment to the anged end of an air supply tube 38, which is preferably valved as is theair supply valve to an ordinary inner tube. The ends of the mold, not shown in the drawing;

are preferably located between or within the ends of the collapsible core so that the core may pro- A ject through the end walls of the mold. The

rubber bandsffeach vis stressed `to take about forty pounpressure when the core is expanded as in Fig.;l ""and'when the core is collapsed as shown in;r 3 these bands are still under tension.

.The etal sleeve or cylinder I5 limitsv the expansibility of the rubber cylinder I4 and there- .that when the core is collapsed the side mem' bers are brought into contact with one another and thus the beveled edges of the side members' may constitute a means for limiting the degree to which the core may be collapsed.

When the core is collapsed the rubber bands 24 are still preferably under tension a less amount, say twenty pounds or less. The rubber bands 24 cause each of the side members to be moved radially inward with respect to the rubber cylinder substantially the same amountl When the metal cylinder i is collapsed it is in the form of substantially a square as shown in Fig. 3 with the corners rounded in order that iiexure of Athe metal which takes place mostly at the corners may not be too greatly l stressed in a small areaas would be the case if the corners or edges were sharper. If the metal i5 cannot b e purchased on the market in tubular form already preshaped, then it may be necessary to make this metal of the desired shape. To accomplish this purpose sheet brass may be rolled into cylindrical form with the edges lapped and soldered. v

In order to localize iiexure at approximately the corners these corners or edges may be given a permanent set by insertion of a mandrel whose edges are rounded to the desired amount and the brass then ironed or rolled over vthe edges of this mandrel to give it a permanent set so that when the rubber cylinder is collapsed the metal cylinder will take the rectangular or square form illustrated in Fig. 3 when the mold has four sides.

To assemble the core shown in Figs." y1 to 3 the sleeve I5 is placed over the Vrubber cylinder i4. The rubber bands.24 are next arranged longitudinally over the metal and rubber cylinders Il and i4. The .headed pins 25 to 2l inclusive are next placed iny position by lifting up a portion of the rubber band and inserting each pin through the pre-formed perforation.

With these pins radially'projecting from the rubber bands the side 'members' i0 to il inclusive and their spacing blockslG to i9 inclusive may next be placed in position around the metal and rubber cylinder withV the rubber bands and their pins arranged in spaces'provided between the blocks i6 to I9 and through the perforations provided in the side members. By taking a pair of sharp pointed pliers or other convenient tool each headed pin may be raised radially outward a suiiicient amount to enable its supporting A pin to be passed through the periorate end. Wheri the supporting pins 29 to 32 inclusive are in position the core is then in collapsed condition ready to receive the fibrous or other water lm pervious envelo'pe which may be slid over' the collapsed core. gether be placed on the core asa unit.

When ready for use the core is .expanded and i placed in the mold with the ends of the core projecting through the walls of the mold. After the concrete or other cementitiousymaterial has at least partially set enough to retain its form and allow withdrawal oi the core, air may be let off from the pressure cylinder i4 in the same way that air is let out of an automobile'tire,

causing the rubber' cylinder I4 to collapse or be- The paperand canvas may tov come of reduced diameter as shown in Fig. 3 and collapsing the metal sleeve i! causing the side members to be moved radially inward until their edges are contiguous, under the in tluence oi.' the rubber bands 24.

'The side members together with the contained metal and rubber cylindersmay then b'e-removed after being collapsed. leaving 'the canvas and p paper in place. After the side members have been removed the canvas and paper will be found to be very easily detachable from the sementitions material, though of course if the paper were allowed to stay in place until the concrete has more completely set` it might be held tightly.

In Fig. 4 is shown another embodiment of this invention which'has been described in my prior copending application Serial Number 115,729 filed December 14, 1936, for Hollow cementitious slab and its process of manufacture, of which this case is a continuation in part. The collapsible core of Fig. 4 includes side members 4B, 4I. 42 and 43- arranged around the rubber tube which is similar to thatA shown in Fig. l except that the side members directly contact with the rubber-tube 44. 'I'he tube 44 is bent out of its cylindrical shape by its contact with the side members. Of course there is a longitudinal tension'rod through the rubber cylinder 44, for the same purpose as mentioned above in connection with Fig. 1.

On the outer surface of each side member is secured a. metal plate 45 and bridging adjacent tially cylindrical shape illustrated. In Fig. 4:V

the" rubber cylinder is what limits the amount or degree to which the core may be collapsed. In event the metal shell of the core does not readily become disconnected from the. partially set concrete, it mayV be released by driving wedges into the mold between-the concrete and the core. yAmong the advantages of this invention may be mentioned the provision of rubber bands or other stressed means for positively collapsing the core. The embodiment illustrated in Fig. 4 may,

it desired, have a paper envelope .around it in4 order to facilitate removal of the core. l 'I'he water impervious fibrous envelope has little or notendency to stick to the partially set concrete. The

provision of a metal envelope which is under tension serves as a convenient limit for the amount of expansiblity of the core. The provision of some appropriate means to limit the degree to which the coremaybe collapsed is another advantageous feature.

An especially noteworthy, eature of the invention shown in Figs. l toidfls the metal cylinderl or sleeve I5 which changd its shape from the cylindrical cross section slMwnin'ljig. 2 to the substantially square or rectangular shape shown in Fig. 3. l

-I claim: v

1. An expansible and ing metallic means for limiting the expansibility of the core, means for expanding said core, re-

collapsible corev includsilient means opposing the said expanding means and' tending to collapse said-core, and means for limiting the degree to which said vcore may and means comprised in said core for limiting the youtward movement of saidv blocks and expansion of said cylinder.

4. An expansible and. collapsible core includ- 4 ing a longitudinal fluid pressure cylinder which is radially expansible and contractiblejangularly spaced substantially rigid blocks around the outside oi' said cylinder and adapted to be moved radially outward by expansion of said cylinder,

and means comprised in said core for limiting the outward movement of said blocks and expansion of said cylinder, saidcylinder being of rubber and having a longitudinal tension rod extending through said cylinder for limiting'longitudinal 4 ing a longitudinal iluid pressure cylinder which expansion thereof.l

v5. An expansible and collapsible core including a longitudinal iluid pressure cylinder which is radially expansible and contractible, angularly spaced 'substantially rigid blocks around the outside of said cylinder and adapted to be moved ,radially outward by expansion of said cylinder, and means comprised in said core i'or limitingthe outward movement of said blocks and expansion of said cylinder, and a water impervious layer-extending around the outside of said blocks and angularly between them forming an envelope .for said blocks and cylinder, atleast a portion of said layer being iiexible enough to allow said envelope to expand.

6. An expansible and collapsible core including a longitudinal iluid pressure cylinder which is radially expansible and contractible, angularly spaced substantially rigid blocks around the outside of said cylinder and adapted to be moved radially outward by expansion of said cylinder, and means comprised in said core for limiting the outward movement of said blocks and expansion of said cylinder, said expansion limiting means including a metal tube enclosing said cylinder and at least portions of which are nexihle enough to bend when said blocks and cylinder are contracted to remove said corefrom a mold.

'7. An expansible and collapsible core includ.- ing al longitudinal iiuid pressure cylinder which is radially expansible and contractible, angularly spaced substantiallyrigid blocks around the outside of said cylinderl and adapted to be moved radially outward by expansion of said'cylinder, and means comprised in said core for limiting the outward movement of said blocks and expansion oi' said cylinder, the adjacent sides of said blocks being bevelled to contact on radial inward movement of said blocks and cylinder whereby' the engagement of one block with one on each 'side thereof may limit the contraction ofsaid core on removal of pressure from said cylinder.

A VA'ff-B "Anexpansible and collapsible core including 'a longitudinal Y`fluid pressure cylinder which is radially expansible and contractible, angularly envelope, and a nbrous water spaced substantially rigid blocks around the out.

" side of said. cylinder and adapted to be moved radially outward by expansion of said cylinder, and means comprised in said core for limiting the outward movement of said blocks and expansion of said cylinder, said expansion* limiting l means including a metal tube enclosing said cylinder and at least portions of which are flexible enough to -bend when said blocksand cylinder are contracted to remove said core'trom a mold,

the bending of portions of said metal tube. oen curring along a line longitudinally. thereof.

9. An expansible core comprising angularly spaced blocks cooperating with an expansible means and forming open spaces `between them when expanded, a canvas4 like envelope surrounding said blocks and bridging the open spaces separating the blocks when `expanded and 'a waterproof coating on said envelope, whereby said core is adapted for use with wet cementitious material to be molded.

10. A collapsible core including ametal tube', means for applying pressure inside said tube and stressing the same by'tension ixrto a substantially circular shape, means for relieving pressure.

Within 'said tube and moving portions 0f the tube walls radially inward to a substantially polygonal cross section with rounded corners whereby sa'ld tube may be repeatedlyv expanded 'and collapsed.

11. An expansible and collapsible core includis radially expansible and contractible angularly spaced substantially rigid blocks around the outside of said cylinder and adapted to be moved radially voutward by expansion. of said cylinder.

and means comprised in said core for limiting 12. A collapsible core including an expansible iluid pressure chamber, a flexible metal envelope around said chamber for limiting expansion thereof, blocks angularly spacedvaround said metal envelope, and a fibrous water impervious envelope around said blocks.

13. A collapsible core including an expansible iluid pressure chamber, a nexible metal envelope around said chamben for limiting expansion thereof, blocks anguiar1y\'spe.ed around said metal impervious envelope around said blocks and tensioned means connecting said blocks outside said metal envelope and tending to move said'blocks radially.

inward. X y

14. n collapsible core including an expansible uid pressure chamber, a ilexible metal envelope around said chamber for limiting expansion thereof, blocks angularly spaced yaround said metal envelope, and a nbrous water'impervlous envelope around said blocks and tensioned means connecting said blocks outside said metal envelope and tending to move said Ablocks radially inward, said tensioned means comprising longithereof. blocks angularly spaced around said metal envelope, and a ilbrous water impervious 'tudinally spaced rubber bands surrounding said envelope armind said block means n metal envelope and secured to said blocks, said.

blocks also being spaced longitudinally and said bands being located longitudinally between said blocks, radially between said metal and brous envelopes, and being hung from supports bridging the space between adjacent blocks.

i6. An expansible and collapsible core including metallic means lor limiting the expansibility ofthe core and means for limiting the degree to which the core may be collapsed, means for expanding said core,- and means opposing said expanding means and at least partially collapsing said metallic means and also at least partially collapsing said second mentioned means.

17. An expansible and collapsible core including metallic means for limiting the expansibility ot the core, means for limiting the degree to which the core may be collapsed, means lfor expanding said core, elastic means opposing said core expanding means and adapted to eect at least a partial collapse of said metallic means a water impervious envelope around said blocks adapted at least in part to be stretched by the blocks in moving outward and strong 'enough alone to support wet cementitious material across the space between each pair of blocks. l

19. A collapsible core including angularly spaced substantially rigid blocks, means within and between said blocks for moving them substantially radiallyV outward. means also within and between said blocks. for moving them substantially radially inward, and a water impervious envelope around said blocks adapted at least in part to be stretched by the blocks in moving outward and strong enough alone to support wet cementitious material across the space between each pair of blocks.

20. The combination with an expansible iluid pressure container, of a metallic tube surrounding and contiguous said container for limiting expansion of the container, a water impervious tube outside the ilrst mentioned tube, blocks spacing the ilrst and second mentioned tubes. and resilient means cooperating with said blocks and adapted on release of fluid pressure to collapse said container and move said blocks toward each other for removal of said blocks, resilient means, metallic tube and container from said water impervious tube.

WALTER H. COBI. 3o 

